With the acceleration of urbanization in China, the development of urban underground pipelines is extremely rapid, and pipelines have become an important part of urban infrastructure and are the “blood vessels” and “nerves” of cities. With the increasing demand for underground pipelines, cities in China are also facing a variety of underground pipe network challenges: urban waterlogging, road ground subsidence, burning and explosion, drinking water pollution and the like. Therefore, the intelligent construction of urban pipelines cannot be delayed.
Sensors are one of the key technological means to realize the intelligentization of equipment and facilities. The fiber grating is a sensing element that is very sensitive to the external environment such as strain, temperature and the like, and distributed multi-point measurement of a single fiber can be achieved through a fiber grating string. In addition, fiber grating sensors have the advantages of light weight, small volumes, high sensitivity, corrosion resistance, anti-electromagnetic interference and the like, and thus are widely used in health monitoring and intelligent control of aerospace and large civil engineering structures.
To realize real-time monitoring and intelligent data analysis of key parameters such as temperature, strain, and pressure in urban underground pipelines, it is necessary to integrate the unique advantages of underground pipe network systems and fiber grating sensing systems to form an intelligent pipeline safety monitoring system to realize safety early warning, fault diagnosis and automatic control of the urban pipe networks.
At present, the fiber grating sensors are mainly surface-mounted and implanted for use. If such a fiber grating sensor is attached to the inner surface of the pipe, the erosion corrosion of the fluid in the pipe is liable to cause debond, shift and even breakage of the sensor; if the fiber grating sensor is attached to the outer surface of the pipe, the sensor is prone to breakage and inactivation due to the bad construction or working environment at the outside of the pipe, thus seriously affecting the test accuracy and service life of the sensor. Therefore, the fiber grating sensor needs to be implanted in the pipe to ensure its survival rate and test accuracy. However, it is very difficult to implant the fiber grating sensor in an industrial continuous extrusion process of the pipe, and implantation of the fiber grating sensor in the continuously extruded pipe is still a technical bottleneck of an intelligent plastic pipe.